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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * The Universal Permissive License (UPL), Version 1.0
 *
 * Subject to the condition set forth below, permission is hereby granted to any
 * person obtaining a copy of this software, associated documentation and/or
 * data (collectively the "Software"), free of charge and under any and all
 * copyright rights in the Software, and any and all patent rights owned or
 * freely licensable by each licensor hereunder covering either (i) the
 * unmodified Software as contributed to or provided by such licensor, or (ii)
 * the Larger Works (as defined below), to deal in both
 *
 * (a) the Software, and
 *
 * (b) any piece of software and/or hardware listed in the lrgrwrks.txt file if
 * one is included with the Software each a "Larger Work" to which the Software
 * is contributed by such licensors),
 *
 * without restriction, including without limitation the rights to copy, create
 * derivative works of, display, perform, and distribute the Software and make,
 * use, sell, offer for sale, import, export, have made, and have sold the
 * Software and the Larger Work(s), and to sublicense the foregoing rights on
 * either these or other terms.
 *
 * This license is subject to the following condition:
 *
 * The above copyright notice and either this complete permission notice or at a
 * minimum a reference to the UPL must be included in all copies or substantial
 * portions of the Software.
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package com.oracle.truffle.regex.util;

import java.util.function.Supplier;

import com.oracle.truffle.regex.RegexSyntaxException;
import com.oracle.truffle.regex.UnsupportedRegexException;

/**
 * Trying to parse and compile a regular expression can produce one of three results. This class
 * encodes the sum of these three possibilities.
 *
 * <ul>
 * <li>the regular expression is successfully compiled: compiledRegex is not null</li>
 * <li>there is a syntax error in the regular expression: syntaxException is not null</li>
 * <li>the regular expression is not supported by the engine: unsupportedRegexException is not null
 * </li>
 * </ul>
 */
public final class CompilationResult<T> {

    private final T compiledRegex;
    private final RegexSyntaxException syntaxException;
    private final UnsupportedRegexException unsupportedRegexException;

    private CompilationResult(T compiledRegexObject) {
        this.compiledRegex = compiledRegexObject;
        this.syntaxException = null;
        this.unsupportedRegexException = null;
    }

    private CompilationResult(RegexSyntaxException syntaxException) {
        this.compiledRegex = null;
        this.syntaxException = syntaxException;
        this.unsupportedRegexException = null;
    }

    private CompilationResult(UnsupportedRegexException unsupportedRegexException) {
        this.compiledRegex = null;
        this.syntaxException = null;
        this.unsupportedRegexException = unsupportedRegexException;
    }

    public static <T> CompilationResult<T> pack(Supplier<T> compilationTask) {
        try {
            T result = compilationTask.get();
            return new CompilationResult<>(result);
        } catch (RegexSyntaxException e) {
            return new CompilationResult<>(e);
        } catch (UnsupportedRegexException e) {
            return new CompilationResult<>(e);
        }
    }

    public T unpack() throws RegexSyntaxException, UnsupportedRegexException {
        if (compiledRegex != null) {
            assert syntaxException == null;
            assert unsupportedRegexException == null;
            return compiledRegex;
        } else if (syntaxException != null) {
            assert compiledRegex == null;
            assert unsupportedRegexException == null;
            throw syntaxException;
        } else {
            assert compiledRegex == null;
            assert syntaxException == null;
            assert unsupportedRegexException != null;
            throw unsupportedRegexException;
        }
    }
}
